Infrastructure, security, and IT leaders · 8 min read
Cloud migrations go wrong in the places proposals skim over: network architecture, licensing that doesn't transfer, and ongoing costs - egress and compute - that aren't in the implementation quote at all. This guide covers what to interrogate before you sign a cloud migration (AWS, Azure, or Google Cloud).
Published 14 June 2026
Download the guide(PDF)VPCs, subnets, transit gateways, firewall rules, and peering are routinely underscoped in migration proposals - and network design errors cause security incidents and performance failures at go-live. Require a network architecture deliverable, not an assumption.
On-premises licences (Windows Server, SQL Server, Oracle DB) cannot always be used in the cloud. Licence repatriation analysis must be completed before the architecture is finalised - cloud licensing can add 20-40% to total cost of ownership if it's discovered late.
Cloud egress (data transferred out) and compute costs are significant, poorly understood, and excluded from implementation proposals. High-egress workloads can make cloud more expensive than on-premises. Model these against real workload patterns before committing.
Application performance in the cloud depends on network latency, data-transfer costs, and resource sizing that can only be validated through load testing in the target environment. Most migration proposals exclude performance testing - put it back in scope.
Identity and access management, secrets management, encryption, logging, and threat detection must be established before workloads migrate, not after. A migration onto an unhardened landing zone is a breach waiting to happen.
Under-scoping the network architecture and ignoring ongoing egress and compute costs. Network design errors cause security and performance failures at go-live, and egress costs - excluded from the implementation quote - can make cloud more expensive than on-premises for high-transfer workloads.
Because the implementation quote omits the ongoing costs: egress (data transferred out), compute at production scale, and licence repatriation, which alone can add 20-40% to TCO. Model these against real workload patterns before signing.
Related guides
From principle to practice
Benchside generates the scope, the interrogation questions, and the lock-in math for your specific vendor - your first project is free.